以下的這個類的功能很簡單，計算你的快取總大小，不管內部快取還是外部快取，和清空快取，包括內部和外部的快取一起清空，請本人親測，效果槓槓的。

public class DataCleanManager {
     
     public static String getTotalCacheSize(Context context) throws Exception {
            long cacheSize = getFolderSize(context.getCacheDir());
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {  
                cacheSize += getFolderSize(context.getExternalCacheDir());
            }  
            return getFormatSize(cacheSize);
        }
   
   
    public static void clearAllCache(Context context) {
        deleteDir(context.getCacheDir());
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {  
            deleteDir(context.getExternalCacheDir());
        }  
    }
   
    private static boolean deleteDir(File dir) {
        if (dir != null && dir.isDirectory()) {
            String[] children = dir.list();
            for (int i = 0; i < children.length; i++) {
                boolean success = deleteDir(new File(dir, children[i]));
                if (!success) {
                    return false;
                }
            }
        }
        return dir.delete();
    }
       
    // 獲取檔案  
    //Context.getExternalFilesDir() --> SDCard/Android/data/你的應用的包名/files/ 目錄，一般放一些長時間儲存的資料  
    //Context.getExternalCacheDir() --> SDCard/Android/data/你的應用包名/cache/目錄，一般存放臨時快取資料  
    public static long getFolderSize(File file) throws Exception {  
        long size = 0;  
        try {  
            File[] fileList = file.listFiles();  
            for (int i = 0; i < fileList.length; i++) {  
                // 如果下面還有檔案  
                if (fileList[i].isDirectory()) {  
                    size = size + getFolderSize(fileList[i]);  
                } else {  
                    size = size + fileList[i].length();  
                }  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        return size;  
    }  
       
    /** 
     * 格式化單位 
     *  
     * @param size 
     * @return 
     */ 
    public static String getFormatSize(double size) {  
        double kiloByte = size / 1024;  
        if (kiloByte < 1) {  
//            return size + "Byte";  
            return "0K";
        }  
   
        double megaByte = kiloByte / 1024;  
        if (megaByte < 1) {  
            BigDecimal result1 = new BigDecimal(Double.toString(kiloByte));  
            return result1.setScale(2, BigDecimal.ROUND_HALF_UP)  
                    .toPlainString() + "KB";  
        }  
   
        double gigaByte = megaByte / 1024;  
        if (gigaByte < 1) {  
            BigDecimal result2 = new BigDecimal(Double.toString(megaByte));  
            return result2.setScale(2, BigDecimal.ROUND_HALF_UP)  
                    .toPlainString() + "MB";  
        }  
   
        double teraBytes = gigaByte / 1024;  
        if (teraBytes < 1) {  
            BigDecimal result3 = new BigDecimal(Double.toString(gigaByte));  
            return result3.setScale(2, BigDecimal.ROUND_HALF_UP)  
                    .toPlainString() + "GB";  
        }  
        BigDecimal result4 = new BigDecimal(teraBytes);  
        return result4.setScale(2, BigDecimal.ROUND_HALF_UP).toPlainString()  
                + "TB";  
    }  
       
       
    
}